The invention relates to a new pyrotechnic shell apparatus, and more particularly to a multiple stage pyrotechnic shell apparatus having enhanced efficiency to increase lift and reduce the risk of one or more of the charges from exploding near the ground.
Multiple stage pyrotechnic shells typically comprise two or more pyrotechnic modules, known as “breaks” that are housed within a single launch tube. A launch charge is located in the tube below the breaks. The breaks are linked to one another and intended to sequentially discharge and produce a pyrotechnic effect once the breaks are launched a safe distance into the sky by the launch charge. Typically each of the breaks is configured in a spherical shape.
Unfortunately, the spherical shape of the breaks in a conventional multiple stage pyrotechnic shell allows the expanding gases from the launch charge to escape between the breaks and the inner surface of the launch tube, resulting in substantial loss of pressure during launch. This limits the launch height of a conventional multiple stage pyrotechnic shell. The limited launch height of a conventional multiple stage pyrotechnic shell therefore presents a greater risk of unacceptable and dangerous low-level discharge of the individual breaks.
In addition, in a conventional multiple stage pyrotechnic shell, the powder weight varies between the breaks in the shell. In particular, traditionally, the break nearest the bottom of the shell has the most powder weight, with each successive break above the bottom break having a successively lower powder weight. This causes the grouping of breaks to tumble during flight and the resultant inefficiency further hinders the ability of the breaks to attain maximum height, and also adds to the risk of unacceptable and dangerous low-level discharge of the individual breaks.
U.S. Pat. No. 6,383,033, for example, discloses a multiple stage pyrotechnic shell apparatus having three breaks. In order to minimize the potential for tumbling, the '033 Patent discloses that the breaks are all uniaxial and the weights of the three breaks are distributed along the central axis such that the center of gravity of the shell is below the vertical midpoint. The shell apparatus of the '033 Patent is further restricted to having a total break weight of less than 40 grams.